Look up aerial lens resolution. Film can't keep up at wider apertures. Some lenses can reportly hit 400 lp/mm. None of this matters for digital. Digital is over loaded at much lower levels. That why the low pass filter is stuck on them. There is no use putting on a high resolution lens on a digital camera.
A crappy consumer zoom is likely better then the sensors can handle.
Second issue. I thought digital was hitting the wall in terms of size. Soon basic physics won't let them put more pixels into that small sensor. That means if they do make a 64M sensor it will need to be a bigger sensor. Meaning the number of pixels per sensor area will be the same. So no increase in quality other then bigger.